PSYCHOLOGY
What good fortune for those in power
that people do not think.
--Adolf Hitler
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Peoples’ Impression of Psychology
With the hope of satisfying their curiosity, many
people listen to talk-radio counselors and
psychics to learn about others and themselves.
http://www.photovault.com
http://www.nbc.com
Dr. Crane (radio-shrink)
Psychic (Ball gazing)
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Ch. 1: Thinking Critically with
Psychological Science
The Need for
Psychological
Science
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Intuition & Common Sense
Many people believe that intuition and common
sense are enough to answer questions regarding
human nature.
Intuition and common sense may help find
answers to questions, but they aren’t error-free.
“Out of sight, out of mind.”
vs
“Absence makes the heart grow fonder.”
Which is it??
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There are limits on “Intuition”
Taxi/ Getty Images
Personal
interviewers may
rely too much on
their “gut
feelings” when
meeting with job
applicants.
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Errors of Common Sense
Try this !
If you were to fold a piece of paper (0.1 mm thick)
100 times, how thick do you think it would be?
800,000,000,000,000 times the distance between
the sun and the earth (93 million miles). Did
you guess much smaller?
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Hindsight Bias
The “I-knew-it-all-along”
phenomenon.
After learning the outcome of
an event, many people believe
they could have predicted
that very outcome. We only
knew Jeffrey Dahmer was a
serial killer after he was
discovered to be a serial killer.
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Overconfidence
Sometimes we think we know more than we
actually know.
How long do you think it would take to
unscramble these anagrams?
Anagram
WREAT
ETYRN
GRABE
8
Anagram
WATER
ENTRY
BARGE
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The Scientific Attitude
The Amazing (James) Randi,
Magician & skeptic: offers $1 million
to anyone who can prove psychic ability
Must be curious, skeptical & humble (able to admit you’re
wrong). You might have to eat your own words!
Critical thinking: thinking that doesn’t blindly accept
arguments & conclusions; rather, it examines
assumptions, discerns hidden values, evaluates
evidence & assesses conclusions.
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The Scientific Method
Psychologists, like all scientists, use the scientific method
to construct theories that organize, summarize and
simplify observations.
• Theory: an explanation that integrates principles and
organizes and predicts behavior or events. For example,
low self-esteem contributes to depression.
• Hypothesis: testable prediction, often prompted by a
theory, to enable us to accept, reject or revise the theory.
Example: People with low self-esteem are apt to feel
more depressed.
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Research for depression would require us to administer
tests of self-esteem and depression. Individuals who score
low on a self-esteem test and high on a depression test
would confirm our hypothesis.
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Research Requirements
• Operational definition: a statement of
procedures (operations) used to define
research variables.
• Must be able to replicate the results
• Replication: repeating the essence of a
research study, usually with different
participants in different situations, to see
whether the basic finding extends to other
participants and circumstances.
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The starting point: Description
Case Study
A technique in which one person is studied in
depth to reveal underlying behavioral principles.
Susan Kuklin/ Photo Researchers
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Clinical
Study
A clinical study
is a form of
case study in
which the
therapist
investigates the
problems
associated with
a client.
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Survey
A technique for ascertaining the self-reported attitudes,
opinions or behaviors of people usually done by
questioning a representative, random sample of people.
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Wording Effects in a survey
Wording can change the results.
• Should cigarette ads and pornography be
allowed on television?
(“not allowed” vs. “forbidden”)
• “aid to the needy” vs. “welfare”
• “revenue enhancers” vs. “taxes”
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• False consensus effect: A tendency to overestimate
the extent to which others share our beliefs and
behaviors.
• Population: all the cases in a group from which
samples may be drawn for a study
• Random sample: a sample that fairly represents a
population because each member has an equal chance
of inclusion (unbiased)
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Naturalistic Observation
Observing and recording the behavior of animals in the
wild and recording self-seating patterns in a multiracial
school lunch room constitute naturalistic observation.
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Correlation
A measure of the extent to which two factors vary together
& how well one predicts the other. When one trait or
behavior accompanies another, we say the two correlate.
Indicates strength
of relationship
(0.00 to 1.00)
Correlation
coefficient
Correlation Coefficient is a
statistical measure of the
relationship between two variables.
r = + 0.37
Indicates direction
of relationship
(positive or negative)
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Scatterplots
Perfect positive
correlation (+1.00)
A scatterplot is a graph comprised of points that are
generated by values of two variables. The slope of the
points depicts the direction, while the amount of scatter
depicts the strength of the relationship.
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Perfect negative
correlation (-1.00)
No relationship (0.00)
The Scatterplot on the left shows a negative correlation,
while the one on the right shows no relationship between
the two variables.
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Data
Data showing height and temperament in people.
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The Scatterplot below shows the relationship
between height and temperament in people. There
is a moderate positive correlation of +0.63.
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Correlation and Causation
or
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Illusory Correlation
The perception of a relationship where no relationship
actually exists. Parents conceive children after adoption.
Conceive
Do not
conceive
Adopt
Confirming
evidence
Disconfirming
evidence
Do not
adopt
Disconfirming
evidence
Confirming
evidence
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Order in Random Events
Given random data, we look for order and
meaningful patterns.
Your chances of being dealt either of these hands is
precisely the same: 1 in 2,598,960.
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Given large numbers of random outcomes, a few
are likely to express order.
Angelo and Maria Gallina won two
California lottery games on the same day.
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Experimentation
Exploring Cause and Effect
Like other sciences, experimentation is the
backbone of psychology research. Experiments
isolate causes and their effects.
Many factors influence our behavior. Experiments
(1) manipulate factors that interest us, while other
factors are kept under (2) control.
Effects generated by manipulated factors isolate
cause and effect relationships.
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An Independent Variable is a factor
manipulated by the experimenter.
The effect of the independent variable
is the focus of the study.
For example, when examining the
effects of breast feeding upon
intelligence, breast feeding is the
independent variable.
A Dependent Variable is a factor
that may change in response to an
independent variable. In psych, it’s
usually a behavior or a mental
process.
For example, in our study on the
effect of breast feeding upon
intelligence, intelligence is the
dependent variable.
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Evaluating Therapies
Double-blind procedure: In evaluating drug
therapies, patients and experimenter’s assistants
should remain unaware of which patients had
the real treatment and which patients had the
placebo treatment.
Random assignment: Assigning participants to
experimental (Breast-fed) and control (formulafed) conditions by random assignment
minimizes pre-existing differences between the
two groups.
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Experimentation
A summary of steps during experimentation.
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Comparison: different research methods
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Statistical Reasoning
Statistical procedures analyze and interpret data
allowing us to see what the unaided eye misses.
Composition of ethnicity in urban locales
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Describing Data
A meaningful description of data is important in
research. Misrepresentation may lead to
incorrect conclusions.
36
Measures of Central Tendency
• Mode: The most frequently occurring
score in a distribution.
• Mean: The arithmetic average of scores in
a distribution obtained by adding the
scores and then dividing by the number of
scores that were added together.
• Median: The middle score in a rankordered distribution.
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A Skewed Distribution
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Measures of Variation
• Range: The difference between the highest and lowest
scores in a distribution.
• Standard Deviation: A computed measure of how much
scores vary around the mean.
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Standard Deviation
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Making Inferences
A statistical statement of how frequently an obtained result
occurred by experimental manipulation or by chance.
1.
2.
3.
When is an Observed Difference Reliable?
Representative samples are better than biased samples.
Less variable observations are more reliable than more variable ones.
More cases are better than fewer cases.
When is a Difference Significant?
When sample averages are reliable and the difference between them is
relatively large, we say the difference has statistical significance.
For psychologists this difference is set at 5%.
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